Tundish having outlet nozzle comprising a swivellable terminal portion

ABSTRACT

A tundish suitable for receiving molten metal to be cast continuously in a continuous casting mould has an outlet for the molten metal constituted by a nozzle the cross section of the bore of which is less than that of the cavity of the mould and a nonrigid joint is included between the outlet of the tundish and the inlet of the mould in order to permit limited inclination of the longitudinal axes of the mould and the nozzle. The part of the nozzle which defines the outlet therefrom is separate from the remainder of the nozzle and is swivellable to a limited extent with respect to the remainder of the nozzle. The longitudinal axes of the mould and the nozzle may be either substantially vertical or substantially horizontal.

United States Patent 3,482,621 12/1969 Halliday Inventor Appl. No.

Filed Patented Assignee Priority Richard James Dain Tonbridge, Kent,England Sept. 6, 1968 Mar. 9, 1971 Ashmore, Benson, Pease & CompanyLimited Stockton-On-Tees, Teesside, England Mar. 20, 1968 Great BritainTUNDISI-I HAVING OUTLET NOZZLE COMPRISING A SWIVELLABLE TERMINAL PrimaryExaminer-.1. Spencer Overholser Assistant Examiner-R. Spencer AnnearAttorney-Holcombe, Wetherill and Brisebois ABSTRACT: A tundish suitablefor receiving molten metal to be cast continuously in a continuouscasting mould has an outlet for the molten metal constituted by a nozzlethe cross section of the bore of which is less than that of the cavityof the mould and a nonrigid joint is included between the outlet of thetundish and the inlet of the mould in order to permit limitedinclination of the longitudinal axes of the mould and the nozzle. Thepart of the nozzle which defines the outlet therefrom is separate fromthe remainder of the nozzle and is swivellable to a limited extent withrespect to the remainder of the nozzle. The longitudinal axes of themould and the nozzle may be either substantially vertical orsubstantially horizontal.

PATENTE'DMAR 9l87| 8568756 SHEET 1 [1F 3 I F/Gil INVENTOR R. J. DMN

EL, WMJM'AQ ATTORNEYS PATENTEDMAR 9 I97I' SHEET ,05 3

IO F/GJ INVENTOR BQTR I. DAIN Mu-L, W M03- o a O a M....L .W H. HM wmwmim vm .UIJJW o o a 0 Q o w o o ATTORNEYS runntsn nnvrno OUTLET nozztscorurmsuzo A SWWELLABILE rsnurnsr. ronnon This invention relates toapparatus suitable for use in continuous casting of metal, particularlysteel. Continuous casting consists essentially of allowing molten metalstored in a container, usually in the form of a tundish, to flow at aregulated rate through a cavity in the mould. In the mould, generallyformed of copper because of its good thermal conductivity properties,the metal is cooled sufficiently for a solid outer skin or shell to beformed which causes the casting leaving the mould cavity to retain thecross-sectional shape of the cavity. By virture of further cooling whichtakes place outside of the mould, and which in most instances isattained by direct application to the casting of a cooling fluid, thecasting solidifies further from the outer skin towards its center.

it is desirable for reasons of safety to the operators of the continuouscasting apparatus and to obtain maximum yield that molten metal storedin the container flows into the mould and that none flows out to wastebetween the container and the mould. Furthermore the metallurgicalqualities of the casting are improved if the flow of metal from thecontainer to the mould taltes place in the absence of air, such anarrangement being known as sealed pouring.

According to a first aspect ofthe present invention, apparatus forcontinuous casting of metal comprises a tundish for receiving moltenmetal to be cast, a continuous casting mould, means defining a passageconnecting the tundish with p the inlet of the mould said means beingsealed to the tundish and the mould to prevent ingress of air and egressof molten metal between the tundish and the mould and means for heatingsaid passage prior to casting.

By providing a sealed passage along which the metal flows between thetundish and the mould, the desiderata mentioned above are attached. Itis however, essential that the passage is dried and thoroughly heatedbefore the molten metal flows therealong and to this end means forheating the passage prior to casting, and which preferably takes theform of an electric heater, are provided.

According to a second aspect of the invention, apparatus suitable forcontinuous casting of metal comprises a tundish for receiving moltenmetal to be cast, the outlet from the tundish for the molten metal beingconstituted by a nozzle, a continuous casting mould having a mouldcavity of greater crosssectional area than that of the bore of thenozzle and with the mould arranged such that the part of the moulddefining the inletthereto is in sealed relation with the part of thenozzle defining the outlet therefrom to prevent ingress of air andegress of molten metal between the nozzle and the mould.

it is essential in continuous casting apparatus that the mo]- ten metalonly solidifies in the mould cavity and not in the passage between thetundish and the mould. It is convenient for this passage to beconstituted by the bore of a nozzle and by ensuring that thecrosssectional area of the passage is considerably less than that of themould two advantages accrue. These advantages are that the heat lossfrom the molten metal in the passage is reduced and the rate of flow ofmolten metal through the passage is increased and therefore it isunlikely that solidification of the metal in the passage will occur.

it is preferable to include a nonrigid joint between the outlet of thetundish and the inlet of the mould in order to permit limitedinclination of the longitudinal axes of the nozzle and the mould andthereby ensure flow of metal into the mould at the same time ensuringthat the outlet of the tundish and the inlet of the mould are in sealingrelation with one another. The part of the nozzle which defines theoutlet therefrom is conveniently separate from the remainder of thenozzle and is .swivellable to a limited extent with respect to theremainder of the nozzle.

To enable the end portion of the nozzle to be swivellable to a limitedextent with respect to the remainder of the nozzle, the two parts of thenozzle are conveniently provided with coacting surfaces each of whichform a part of the surface ofa sphere. The coacting surface on one ofthe parts of the nozzle forms a socket for receiving a convex surface onthe other part of the nozzle. The coacting surfaces enable the outerpart of the noule to be rotated to a limited extent relative to thestationary remainder of the nozzle so that their longitudinal axes aremutually inclined while the coacting surfaces remain in contact with oneanother.

Means are provided which bias the coacting surfaces of the nozzle intoabutting sealed relation.

The axes of the mould and the nozzle may be arranged substantiallyvertical so that the casting leaves the mould in a substantiallyvertical direction. The axes of the mould and the nozzle may also bearranged to be substantially horizontal in which case the tundish mayhave an upwardly facing opening to receive the molten metal and a narrowthroat extending downwardly from the base of the inner wall of thetundish to the inner end of the nozzle. A vertically displaceablestopper rod may be associated with the throat to stop and start the flowof molten metal from the tundish to he mould. Preferably an aperture isprovided in an outer sidewall of the tundish opposite the nozzle with apassage extending from the aperture to the inner end of the nozzle. Thelongitudinal axis of the passageway is aligned with that of the nozzleso that a heater may be inserted into the passage to preheat the passageand nozzle prior to casting. During casting the aperture is closed witha removable refractory plug. The plug may be removed in an emergency todrain metal from the tundish through the aperture if a blockage occursin the mould and there is a likelihood that the molten metal willotherwise freeze in the tundish.

In order that the invention may be more readily understood it will nowbe described, by way of example only, with reference to the accompanyingdrawings in which:

FIG. 1 is an elevation, partly in section of a tundish and mould withthe longitudinal axis of the mould cavity arranged vertically;

FIG. 2 is a sectional side elevation of a tundish and mould with thelongitudinal axis of the mould cavity arranged horizontal; and v FIG. 3is a plan view of the arrangement shown in FIG. 2.

Referring to FIG. 1, a tundish 1 arranged to receive molten metal to becast continuously in a continuous casting mould 2 is supported on arigid frame 3. The tundish is lined with a refractory material 4 and apassageway 5 extends from the base of the inner wall of the tundish tothe inlet of the mould cavity 6. The mould 2 is positioned beneath thetundish with thelongitudinal axis of the mould cavity vertical and thepassage 5 is defined by a nozzle 7 of refractory material.

The nozzle extends from the outlet of the tundish to the inlet of themould cavity so that molten metal flows from the tundish to the mould inthe absence of air. A vertically displaceable stopper rod 8 in thetundish has its lower end associated with the upper end of the nozzle inorder to control the flow of molten metal from the tundish into thenozzle.

The nozzle comprises two parts 9 and I0 and to enable one part of thenozzle to be swivellable to a limited extent with respect to the otherpart of the nozzle, the two parts of the nozzle are provided withcoacting surfaces 11 and 12 respectively each of which forms a part ofthe surface of a sphere. The coacting surface on the part 9 of thenozzle is of concave form and serves as a socket for receiving thecoacting surface of convex form on part 10 of the nozzle. The coactingsurfaces enable the two parts of the nozzle to be inclined slightlyrelative to each other while the coacting surfaces remain in contactwith one another. This arrangement ensures that the metal flows from thetundish to the mould through a sealed passageway while enabling thetundish and the mould to be assembled with the longitudinal axes of theoutlet of the tundish and the inlet to the mould slightly out ofalignment.

In order to prevent leakage between the coacting surfaces 111 and 12 themould is rigidly secured to a framework 13 while the tundish may beraised or lowered slightly with respect to the framework 13 and isbiased downwardly towards the framework 13 by means of cotters 14projecting through slots in pegs 15 extending through openings in asupport plate 16 for the tundish. In this way the coacting surfaces arebiassed together in abutting relation and this prevents leakagetherebetween.

Prior to introducing molten metal into the tundish the tundish and thepassage 5 are dried and preheated by a gas burner extending to thetundish through the upper open end.

Referring now to F165. 2 and 3 a metal tundish 20 has an inner lining 21of refractory material, such as fire clay, which defines the inner wallof the tundish. A narrow throat 23 extends downwardly from the base ofthe inner wall of the tundish and is in communication with the bore 24of a nozzle 25 projecting outwardly from a sidewall of the tundish. Theaxis of the bore of the nozzle is substantially horizontal as also isthe axis of the cavity of a continuous casting mould 27 which is sealedto the nozzle. The nozzle is of refractory material and is in two parts,namely a fixed part 28 mounted in the tundish and a part 29, which formsthe outer end of the nozzle and which is swivellable with respect to thepart 28. The part 28 of the nozzle has a concave surface which is partof the surface of a sphere and which coacts with a similar convexsurface 31 on the part 29 of the nozzle. The two parts of the nozzle maybe arranged with their longitudinal axes inclined one relative to theother by a limited amount but with the coacting surfaces 30 and 31remaining in contact with one another.

The tundish has an upwardly facing opening to receive molten metal and avertically displaceable stopper rod 32 associated with the throat tocontrol the flow of molten metal from the tundish. The mould 27 issecured to the tundish 1 by means of a plurality of bolts 32 which arespaced apart around the projecting end of the nozzle and the end of thenozzle abuts against an annular plate 33 which may be of graphite orsilicon nitride and which defines the inlet to the mould. A spring 34 isprovided around each of the bolts 32 to engage with the head of the boltand a part of the mould to bias the mould and the tundish together andthereby clamp the coacting surfaces of the nozzle together in sealedrelation. The springs 34 provide a degree of resilience which keeps themould and the tundish biassed together when differential expansionoccurs between the mould and the tundish when the apparatus is in use.

The cross-sectional area of the bore of the nozzle 24 is considerablyless than the cross-sectional area of the mould cavity so that moltenmetal flowing from the tundish to the mould passes through the nozzle ata higher rate than would be the case if the cross section of the bore ofthe nozzle and the cavity of the mould were comparable. The heat lossfrom the bore of the nozzle is also reduced due to the relatively smallcross section of the bore and both the fast rate of flow of the metalthrough the bore and its small cross-sectional area prevent metalsolidifying in the bore and hence blocking it. An aperture 40 isprovided in the sidewall of the tundish opposite the nozzle 25 and apassageway 41 extends into the tundish from the aperture to the throat23. The axis of the passageway 41 is substantially horizontal and isaligned with the axis of the nozzle. A removable refractory plug 42 isfitted into the aperture 40 and part way into the passageway to preventleakage therethrough when metal is contained in the tundish. The plughas a tapered outer surface which engages with a correspondingly taperedsurface 43 defining part of the length of the passageway. A horizontallydisplaceable stopper rod 44 has a threaded portion 45 which projectsthrough the plug to the outside of the tundish and engages with a nut 46mounted on the outside of the plug so that the stopper rod can beadvanced into'engagement with a part of the passageway 41 which is ofreduced cross section to prevent leakage of molten metal through thispassageway. The plug is retained in the aperture by quick releaselocking means 47.

Prior to casting the plug 40 and the stopper rod 44 is removed and aheater inserted into the passageway 41 and the bore of the nozzle 24 todr and re-heat them. After the plug has been replaced, the mo ten 5 eelto be cast [8 poured mto the tundish through the upwardly facing openingand the stopper rod 32 is raised slightly to enable molten metal to flowthrough the throat 23 and the nozzle 24 to the mould. The mould iscontinuously cooled and further cooling means in the form of nozzles(not shown) are positioned adjacent the outlet end of the mould so thatcooling fiuid can be directed on to the casting leaving the mould. Means(not shown) are provided for withdrawing the casting continuously fromthe mould and tundish may be reciprocated in a direction parallel to teeaxis of the mould in order to prevent sticking of the metal to themould.

I claim:

1. ln apparatus adapted for use in the continuous casting of steel,which apparatus comprises a tundish for receiving molten metal to becast, said tundish having a vertically disposed outlet defined bythermoinsulating material, a narrow throat defined by thermoinsulatingmaterial connecting said outlet with the inlet of a substantiallyhorizontal tubular nozzle projecting laterally outward from one of apair of opposite sidewalls of the tundish; a continuous casting mouldsecured to said wall of the tundish with the longitudinal axis of themould cavity substantially horizontal, the cross-sectional area of thecavity being greater than that of the nozzle bore, and said mouldcomprising an apertured silicon nitride plate constituting the inlet ofthe mould; means biassing said plate into engagement with the outlet ofthe nozzle so that the bore of the nozzle is in sealed relation with themould cavity to prevent ingress or air and egress of metal between thenozzle and the mould; and means for admitting a heater to said throat,said means comprising an aperture defined by the sidewall of the tundishopposite to that from which the nozzle projects, a passage defined bythennoinsulating material extending from said aperture to said throatwith the longitudinal axis of the passage aligned with the axis of thebore of the nozzle, the cross-sectional dimensions of the aperture andpassage being large enough to permit a heater to be passed therethroughinto said narrow throat, a removable sealing plug fitted into saidaperture and a passage, and quick release locking means on said tundishfor securing said plug in position, the improvement according to whichsaid nozzle comprises two parts, one of which constitutes the inlet ofthe nozzle and extends to the sidewall of the tundish and the other ofwhich constitutes the outlet of the nozzle, said two parts of the nozzlehaving coacting part-spherical surfaces, which permit the longitudinalaxes of the bore of the two parts of the nozzle to have limitedinclination relative to each other while the surfaces remain in contactwith one another.

2. Apparatus as claimed in claim 1 in which the coacting surface on thepart of the nozzle defining the outlet therefrom is of convex form andthe coacting surface on the remainder of the nozzle is of concave form.

3. Apparatus as claimed in claim 1 in which said nozzle is of refractorymaterial.

1. In apparatus adapted for use in the continuous casting of steel,which apparatus comprises a tundish for receiving molten metal to becast, said tundish having a vertically disposed outlet defined bythermoinsulating material, a narrow throat defined by thermoinsulatingmaterial connecting said outlet with the inlet of a substantiallyhorizontal tubular nozzle projecting laterally outward from one of apair of opposite sidewalls of the tundish; a continuous casting mouldsecured to said wall of the tundish with the longitudinal axis of themould cavity substantially horizontal, the cross-sectional area of thecavity being greater than that of the nozzle bore, and said mouldcomprising an apertured silicon nitride plate constituting the inlet ofthe mould; means biassing said plate into engagement with the outlet ofthe nozzle so that the bore of the nozzle is in sealed relation with themould cavity to prevent ingress or air and egress of metal between thenozzle and the mould; and means for admitting a heater to said throat,said means comprising an aperture defined by the sidewall of the tundishopposite to that from which the nozzle projects, a passage defined bythermoinsulating materiAl extending from said aperture to said throatwith the longitudinal axis of the passage aligned with the axis of thebore of the nozzle, the cross-sectional dimensions of the aperture andpassage being large enough to permit a heater to be passed therethroughinto said narrow throat, a removable sealing plug fitted into saidaperture and a passage, and quick release locking means on said tundishfor securing said plug in position, the improvement according to whichsaid nozzle comprises two parts, one of which constitutes the inlet ofthe nozzle and extends to the sidewall of the tundish and the other ofwhich constitutes the outlet of the nozzle, said two parts of the nozzlehaving coacting partspherical surfaces, which permit the longitudinalaxes of the bore of the two parts of the nozzle to have limitedinclination relative to each other while the surfaces remain in contactwith one another.
 2. Apparatus as claimed in claim 1 in which thecoacting surface on the part of the nozzle defining the outlet therefromis of convex form and the coacting surface on the remainder of thenozzle is of concave form.
 3. Apparatus as claimed in claim 1 in whichsaid nozzle is of refractory material.